During the past year we have studied gonadotropin and inhibin pulsatility in 88 normal pubertal children. We have complete studies of LH, FSH, inhibin and testosterone pulsatility in 10 fully pubesced males and 14 prepubertal males. We have shown that inhibin release is pulsatile, that the mean levels of inhibin increase in males as they progress through puberty. In addition, we have shown that the number of peaks of inhibin in a given sampling period does not increase during puberty though the peak height does increase. This pattern of increase of peak height, but not peak number, is the same as that for FSH. LH and testosterone peak numbers and peak heights increase throughout puberty. We have also shown that inhibin increases in response to an intravenous bolus of LHRH. It also appears that the mean levels of inhibin are different in males and females. We are currently working with the statisticians to develop a method for analyzing coincidence of pulses of the hormones studied. In addition, we have begun to study how inhibin, testosterone and gonadotropin pulsatility changes during the day in a cross-sectional study and how release of these hormones changes in a population of children followed longitudinally throughout puberty. We have begun to study children with abnormalities of puberty, including gynecomastia, delayed puberty and cryptorchidism. We plan to study children with exposures to environmental toxins with estrogenic activity, lead, and estrogen-containing hair products. By the end of the summer, we will have entered ten girls in the evaluation of treatment effectiveness of Depot Lupron. We have begun a collaboration with a pediatric endocrinologist at Walter Reed Army Hospital to study a subset of their patients that were found to have had exposure to estrogens through hair products. In this project, we will also work with Dr Ken Korach to study this question on a mechanistic level.